Calculator: Remove "Make it look nice" extra credit (#29004)

Generally not recommended by the team and community for more productive learning.
People who are dead set on making it look nicer will do so anyway, whether we suggest it or not.
This extra credit can be removed to aide more people with being more productive with this project.

foundations/javascript_basics/project_calculator.md

@@ -45,7 +45,6 @@ Here are some use cases (abilities your project needs to have):
 #### Extra credit
 
 - Users can get floating point numbers if they do the math required to get one, but they can't type them in yet. Add a `.` button and let users input decimals! Make sure you don't let them type more than one though: `12.3.56.5`. It is hard to do math on these numbers. \(disable the decimal button if there's already one in the display\)
-- Make it look nice! This is a great project to practice your CSS skills. At least make the operations a different color from the keypad buttons.
 - Add a "backspace" button, so the user can undo if they click the wrong number.
 - Add keyboard support!